A chemically synthesized oligoribonucleotide (oligo RNA) may be used as a RNA probe for gene analysis; materials for RNA pharmaceuticals such as antisense RNA, ribozyme RNA, and gene interference by means of iRNA; artificial enzymes, and an adaptor.
A RNA derivative having a methyl ether group at its 2′ hydroxyl group is commercially available and widely used as that of an ether-type. However, this modified RNA has a disadvantage with respect to enzyme-resistance in cells when it is used as a gene-controlling agent. Another ether-type modified RNA widely used is one having a methoxyethylether group. This modified RNA was reported to be superior in the enzyme-resistance to that having the methyl group (Non-Patent Document 1). However, there is no common way for the synthesis of the methoxyethylether-type modified RNA with the use of pyrimidine and purine nucleosides due to limitations in a method and agent for the introduction of said group. Furthermore, as the structure of its ether chain is restricted due to an oxygen atom present therein, it is very likely that a problem will occur with respect to condensation efficiency in the synthesis of the oligo RNA.
In order to overcome the above problems, it is necessary to develop an ether-type modified RNA with a group of around three carbon atoms that has a hydrophilic and electron-accepting substituent at its end but no oxygen atom in the ether chain.
Non-Patent Document 1: Von Pierre Martin, Helvetica Chimica Acta 1995, 78, 486-504